If you are caught driving a vehicle you are not insured to drive you could receive a fixed penalty of £300 and 6 penalty points. If the case goes to court you could get an unlimited fine and be disqualified from driving.
Leasing Options have compiled a list of ways you could be invalidating your car insurance without even realising...
9. Making a profit from charging people for lifts
Making a profit from charging people for lifts could put your car insurance at risk. However if you are just accepting petrol money, which does not result in any money as profit, then this is not considered illegal and will not change your insurance.
10. Modifying your car
If you plan on modifying your car, contact your insurer beforehand so they can tell you how much your policy will increase. Modifying your car increases insurance policies for multiple reasons. Bodywork and non-standard engines are more expensive to replace and repair. In addition to this, some modifications can increase the risk of your car being a victim of theft.